Cobalt

Cobalt (Co) is an essential element, as a component of cyanocobalamin (Vitamin B12). It is also used industrially in the manufacture of high-strength alloys used for cutting/drilling tools, in the semi-conductor industry and as a pigment. Dicobalt Edentate is used in the treatment of cyanide poisoning.

Analysis of cobalt concentration is of little use in the determination of vitamin B12 deficiency, but is useful to assess occupational and environmental cobalt exposure. Chronic exposure to inorganic cobalt salts, either by ingestion or inhalation of dust, causes respiratory distress, dyspnoea, pneumonconiosis, or can lead to cardiomyopathy. Inorganic cobalt can induce haemoglobin synthesis, as well as hypertriglyceridaemia and hypercholestrolaemia.

Cobalt is quickly cleared through the kidneys, and urine cobalt measurements are a useful indicator of recent exposure.

A large number of hip replacements are carried out in the UK every year (>50,000), with the Metal-on-Metal (MoM) type gaining in popularity.

The Medical Devices Alert (MDA/2012/008) issued in February 2012 by the MHRA has, however, highlighted that MoM prosthesis failure in some patients may arise from localised tissue reactions associated with the release of particulate metal ions during articulation. Cobalt (Co) and Chromium (Cr) are the key components in the metallic alloy used in the manufacture of these MoM prostheses: The MHRA has thus recommended following up patients who have undergone MoM hip replacement on an annual basis for at lease 5 years, with the measurement of Co and Cr carried out in symptomatic/suspected patients. The MDA document outlines a plan of action based on the concentrations measured.